ABSTRACT
OBJECTIVE: To examine the effects of coculture with human oviductal cells regarding the development of 1-cell stage ICR mouse embryos and to investigate the effects of duration and start time of coculture. MATERIALS AND METHODS: ICR mice were superovulated with PMSG/hCG and 1-cell stage mouse embryos were recruited. 1-cell mouse embryos were cocultured on human oviductal cells in a CO2 incubator(coculture group) and were cultured on 0.4 % BSA+HTF media(control group)(Experiment 1). 1-cell mouse embryos were cocultured on human oviductal cells for 36, 44, 52, 60 hours after hCG IP respectively, and then were transferred to 0.4 % BSA+HTF media(Experiment 2). In comparison, 1-cell mouse embryos were cultured by using 0.4 % BSA+HTF media, and then were transferred to human oviductal cell coculture system using the same schedule(Experiment 3). Afterward, they were examined regarding the development to 2-cell, 4~8 cell stage mouse embryos, morulas and blastocysts. RESULTS: In experiment 1, the developmental rates to 2-cell embryos of coculture group and control group were 97.3 % and 98.7 %, respectively. After 2-cell embryos, coculture group showed significantly higher developmental rate than control group (p<0.05). In experiment 2, the developmental rates after 2-cell embryos showed the significant differences. The groups with coculture effects removed before post-hCG 60 hours showed significantly lower developmental rates (p<0.05). In experiment 3, the developmental rates after 2-cell embryos were higher when the coculture started at an earlier stage. Furthermore, the groups which were cocultured from post-hCG 52 hours exhibited significant lower developmental rate than the groups which were cocultured continuously (p<0.05). CONCLUSION: The coculture with human oviductal cell could improve the development of the embryos in vitro and might mimic the natural physiological condition better than media environment. The degree of improvement was more pronounced when the coculture started at an earlier stage and the duration of coculture was longer. More importantly, the changes of culture condition at post-hCG 52 hours in which secondary mitosis occurs, have significant detrimental effects on growth and development of mouse embryos.